100,000 tiny worldlets share an orbit around their star. At only 40km wide, they shouldn't have appreciable gravity, let alone atmospheres, but that's not the oddest part: these planetoids share a band of atmosphere some 25,000km wide.

This river of air is somehow contained (perhaps by the same force that makes the planetoids stay apart from one another, and grants them 1g at the surface). Much of it is like the upper atmosphere of Earth, becoming thin near the edges and tropospheric within 100km of a planetoid.

Naturally, human beings live on these worlds. On average, the worldlets are about 9-10 thousand km apart (at extremes, a b-52 can fly 18k km without refueling, for comparison), and given their size and number, they have about the same surface area as Earth. Some are oceanic (many, in fact). Some are nearly all desert (perhaps due to some kind of air current phenomenon in the air belt). The most densely populated ones are temperate, with moderate quantities of surface water.

It is currently a time of interplanetary empires. About 400 years ago, semaphore signals were first used to communicate among the countless worlds; a few wind-tossed fire balloons were successful before that, but completely unpredictable as a method of communication. Some 280 years ago, the first powered flight was developed, and the technology (and the empires that commanded it) has spread to most worlds as it matured. The most modern aircraft can be small shrikes with a single pilot, or great vast behemoths with hundreds of crewmen.

I posit that the small population pools will slow the advancement of technology compared to Earth's history. The flying machines these people use are in many ways like mid-wwII aircraft. Props, limited electronics, and a sense of experimentalism are likely in any design.

Radio is known in theory, but it's not been developed yet. Putting it into any kind of practice calls for a heroic inventor. Jet propulsion, advanced firearms, clever logistical tricks and computing machines... these are all hypotheticals that a clever PC could invent or encounter.

As the empires and free agents chart and trade the skies, they encounter remnants of cities far older than anything in the settled world... dead or deserted worldlets are known, of course, but some have ruins untouched for a thousand years... and two thousand... and ten thousand....

Even the oldest ruins show signs of advanced metalworking beyond even the achievements of the greatest empires. Metals that haven't corroded even though the stone they rest on has eroded beneath them. vaults containing strange machines unrecognizable to man....

Who -- or what -- is wiping clean the slate of history? And how soon will it strike again?

To continue, that's the larger question, but the smaller questions are no less interesting sources for adventure: What's within these ruins here? Why did the Imperial Outpost on Devarlorian go dark? Who assassinated the Chancellor mid-flight to the council meeting? When did the galley crew last clean out the kettles? Where can we escape the High Church's dictates?

I love it. It has a lively pulpiness and luscious exotic island hopping feel. It also reminds me of how early 1960s comic books handled the asteroids. A GM could take this in any of a thousand ways, lovely.

In 1923 Randolph Carter, while exploring caves in New England, discovered a system of nexal gates leading to far places. A few lead to places on Earth, others to Mars and other worlds around our sun. The gates that fascinated everyone led to extra-solar planets.

Carter's explorations led to the realisation that most of the lifeforms on these worlds came from the Earth. He theorised that whoever created the gates meant to spread Earth's lifeforms far and wide. Perhaps because the conditions for life to start and to become complex and abundant were rare and Earth was especially rich in lifeforms.

Carter's people found human groups from Native American tribal groups (bands of the Mi'kmaq People) to large civilizations of many different origins. Boston, having a nexal gate under Beacon Hill built a subway to a large city settled by a mixture of Gaelic speakers and Narragansetts.

The early enthusiasm for these gates was somewhat dimmed when a plague spread from one of these worlds to the Earth in 1939(some people say the plague was a good thing because Hitler and Stalin both died and thus we were spared a second great war, other say the horrors of 1914-1918 taught Europe to avoid general war for all time). After the Plague was beaten by penicillin the USA focused on exploring the stars through these gates and spreading out to the stars.

During the celebrations of the Tricentennial of Randolph Carter's discovery something happened. No one knows what. But the gates to Earth are closed. But the settlers from Earth settled on the worlds of a thousand stars have stardrives and the engineers to build and crew starships. The journey to Earth shall be made. The Mi-Go and others advise against this or threaten, but humanity is undaunted.

Should I have pointed out that this is a mixture of Star Trek and Lovecraft? Of course, the quest for Earth theme is very Roads of Heaven. Which means that the campaign can go in mystical and/or occult directions.

I love it. It has a lively pulpiness and luscious exotic island hopping feel. It also reminds me of how early 1960s comic books handled the asteroids. A GM could take this in any of a thousand ways, lovely.

The theory is that the attempt of a group of researchers to scan the later Jurassic period, around 152 million years ago, botched. The botch sent the cities around a dozen major universities back in time.

Luckily, late TL9 cities with cheap fusion and vertical agriculture are less fragile than most earlier cities. But the next generation was still brutal. Now, fifty years after the transference, the cities have become stable. Now there is an urge to explore this alien Earth.

On January 1st, 2030 the people of the United States of America, Canada, and Indonesia (plus a cluster of other nations equaling one tenth of Earth's population, give or take a few million) woke up on a planet other than the Earth.

After a period of disorientation, people figured out the following.

1) They were on a terraformed planet.

2) They didn't know what star system they were in probably because they were at least 75,000 lyrs away from Earth if not much further.

3) Everyone older than 25 was now 25 again. Also, everybody was in perfect health and knew how to use their new healthy bodies. I.e. people who had been born without legs now knew how to walk and run. Etc.

4) They were now surrounded by highly advanced technology (TL12^) and knew how to use and maintain it and the principles the tech worked by.

5) All humans were now telepathic and also had TK (anti-social and violent individuals excluded). Everybody, even those lacking other psi powers, has Mind Shield powers.

The people now wanted answers. Why? Where are the other Humans? And where is Earth?